A conventional WCDMA radio interface has a three-layered channel structure, the physical channel, the transport channel, and the logical channel, so as to flexibly respond to various service providing types and cases of a multi-call (for example, a simultaneous transmission of a voice call and a multimedia call).
As shown in FIG. 1A, the protocol configuration of, the WCDMA radio interface includes a layer 1 (a physical layer), a layer 2 (a data link layer), and a layer 3 (a network layer). The logical channels are defined by the service access points between the layer 3 and the layer 2, and the transport channels are defined by the service access points between the layer 2 and the layer 1. The layer 2 is divided into two sublayers: a Radio Link Control (RLC) sublayer for controlling a radio link and a Media Access Control (MAC) sublayer for, for example, allocating radio resources.
The physical channels are provided for realizing the transmission of the transport channels via actual radio transmission paths and mapped to radio resources on time, frequency, or code areas as transmission channels between radio nodes (a base station and a mobile station) of the layer 1.
The transport channels are provided, as described above, between the physical channel and the MAC sublayer of the layer 2. Further, the transport channels are classified depending on transmission forms as shown in FIG. 1B and feature which and how information is transmitted.
In a conventional WCDMA radio interface, a circuit-switching type data transmission is realized by allocating a dedicated channel (DCH) for each user (see “W-CDMA mobile communication method” edited by Keiji TACHIKAWA, pp. 97-99).
Further, in the common transport channels where data are transmitted and received by sharing radio resources by the users in a service area of a base station, each of a downlink broadcast channel, a paging channel, and a forward access channel does not have any relationship with an independent physical channel, and is mapped to a common control physical channel.